1. Field of the Invention
The present disclosure relates to a vacuum cleaner. More particularly, the present disclosure relates to a connecting tube having a dust sensing function for use in a vacuum cleaner, which can detect whether there is dust or dirt on a surface to be cleaned and inform a user of the detected result in cleansing.
2. Description of the Related Art
Generally, in cleaning, a vacuum cleaner generates a strong suction force by using a suction motor, so that it draws in dust or dirt from a surface to be cleaned thus to clean the surface to be cleaned. Accordingly, the vacuum cleaner is very useful in cleaning dust or dirt adhered to the surface to be cleaned, such as a carpet, a floor and the like.
However, when a user cleans the surface to be cleaned using the vacuum cleaner, she or he can easily perceive whether there is dust or dirt on the surface to be cleaned in a cleaning area contaminated or soiled with relatively large dust or relatively conspicuous dirt, but can not easily perceive whether there is dust or dirt on the surface to be cleaned in a cleaning area soiled with relatively minute dust.
To address the problem as described above, an electric vacuum cleaner in which a rotating blade and an electric generator driven by the rotating blade are installed on a dust suction passage, such as an extended tube or the like, is disclosed in Japanese Patent Laid-open No. H 11-76120. The rotating blade is rotated by an external air, which is drawn in due to an air suction force in the dust suction passage. The electric vacuum cleaner is configured, so that in cleaning, the electric generator driven by the rotating blade generates an electric power to operate a dust sensor and the like and thus the dust sensor informs a user of whether there is dust or dirt drawn in a suction nozzle or the dust suction passage in which it is installed. Accordingly, the user can perceive whether there is the dust or dirt on the surface to be cleaned or whether the dust or dirt is completely removed from the surface to be cleaned according to the operation of the dirt sensor in cleaning.
However, in the electric vacuum cleaner as described above, since the rotating blade driving the electric generator is rotated by the external air, which is drawn in due to the air suction force in the dust suction passage, there is a problem in that when the rotating blade is rotated by the external air and when the external air is mixed with air in the dust suction passage, noises can be generated. The noises may cause the vacuum cleaner to deteriorate in quality.